Explosion-proof panel board with offset mounting



Oct. 5, 1965 A. l. APPLETON 3,210,609y

EXPLOSION-PROOF PANEL BOARD WITH OFFSET MOUNTING Filed Feb. 20. 1961 2 Sheets-Sheet l 29 A'r'rvs.

A. l. APPLETON 3,210,609

EXPLOSION-PROOF PANEL BOARD WITH OFFSET MOUNTING Oct. 5, 1965 2 Sheets-Sheet 2 Filed Feb. 20, 1961 INVENToR. ARTHUR [APPLE-rau BY M, W aw,

A-rwsl United States Patent O "ice 3,210,609 EXPLOSION-PROOF PANEL EGARD WITH OFFSET MOUNTING Arthur I. Appleton, Northbrook, lil.

(1713 Wellington Ave., Chicago 13, lll.) Filed Feb. 20, 1961, Ser. No. 90,410 Claims. (Cl. 317-119) The present invention relates to electrical panel boards of the explosion-proof type and which are adapted to accommodate a plurality of circuit breakers and their associated wiring. It represents a modification of the panel board construction disclosed in my copending application Serial No. 81,787, filed in the United States Patent Oiiice on January l0, 1961.

Explosion-proof electrical fixtures are designed for use in areas where explosive or inflammable mixtures of gas or vapor are present in the surrounding atmosphere and likely to filter into the fixture. When this occurs, an arc within the fixture due, for example, to operation of a circuit breaker orto an electrical breakdown, is likely to trigger an internal explosion. Fixtures such as explosionproof panel boards must, accordingly, be capable of tolerating an internal explosion in such a manner that it is not permitted to trigger a further explosion in the surrounding atmosphere.

Heretofore, explosion-proof panel boards have been unwieldy, complex, and expensive structures, particularly where ya number of circuit breakers are to be protectively enclosed. Moreover, where attempts have been made to facilitate installation and servicing of the circuit breakers, the complexity of the actuating linkage and sealing arrangement has correspondingly increased.

One object of the present invention is to provide yan explosion-proof panel board of the character set forth and which will be more compact yet capable of accommodating a substantially greater number of circuit breakers and their associated w-iring than possible in explosionproof panel boards of the type heretofore known.

Another object of the invention is to provide an explosion-proof panel board of the character set forth including ya circuit breaker housing having opposed actuating and access panels and a mounting arrangement rendering both said panels immediately accessible for operation or servicing.

Other objects and advantages will become apparent as the following description proceeds, taken together with the accompanying drawings, in which:

FIGURE l is a front elevational view of an explosionproof panel board exemplifying the invention, and including certain parts shown in vertical section.

FIGS. 2 and 3 are, respectively, side and rear elevational views of the panel board of FIG. 1.

FIGS. 4 and 5 are enlarged vertical sectional and elevational views, respectively, detailing the sealed connecting means between the breaker housing and terminal housing in the panel board of FIGS. l, 2 and 3.

FIGS. 6 and 7 are enlarged, fragmentary plan and vertical sectional views, respectively, `showing an alternative form of sealed conecting means for use between the terminal and breaker housings of the device of FIGS. 1 to 5.

FIG. 8 is an enlarged fragmentary plan view illustrating a further modification of the device of FIGS. l to 5 involving a pair of sealed connecting members interposed between the terminal and breaker housings.

FIG. 9 is a vertical sectional view taken in the plane of the line 9 9 through the device illustrated in FIG. 8.

FIG. 10 is a fragmentary front elevational View through an explosion-proof panel board similar to the ones shown in FIGS. l to 5 but including a bottom entrance and exit for the system wiring.

Patented Oct. 5, 1965 FIG. ll is a fragmentary bottom plan view of the panel board illustrated in FIG. l0.

While the invention is susceptible of various modifications and alternative constructions, certain illustrative embodiments have been shown in the drawings and will be described below in considerable detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but, on the contrary, the intention is to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the invention as expressed in the appended claims.

Referring more specically to FIGS. l to 5, inclusive, the present invention is there exemplified in an illustrative explosion-proof panel board 20 adapted to accommodate .a number of individual circuit breakers 21. The breakers 21, in this instance six in number, are enclosed in an explosion-proof breaker housing 22 of box-like construction with a breaker housing chamber 24 defined therein. One wall of the breaker housing 22 comprises a breaker actuating panel 25 having a plurality of levers 26 thereon for switching and resetting the circuit breakers 21. The opposite wall of the breaker housing 22 comprises an access panel 27 having a relatively large .aperture or port 2S providing ready access to the circuit breakers 21 for installation or maintenance without disturbing the actuating panel 25. The access port 28 is closed by a threaded cover 29 fitted in explosion-proof sealed relation with the breaker housing.

The panel board 20 includes a terminal housing 30 also of box-like form and having an explosion-proof terminal chamber 31 dened therein. In the present instance, the terminal housing 30 is integral with and arranged in the same unitary assembly as the breaker housing 22. The terminal housing chamber 31 and breaker housing chamber 24 are separated by internal partition wall 32 which defines an explosion-proof barrier therebetween. The wall 32 in this case includes a sealed connector fitting 33 which carries electrical conductors 35 between the two chambers but includes an explosion-proof seal 34 physically isolating the two-chambers (FIG. 4). The terminal housing also includes a terminal block assembly (not shown) to which external circuitry may readily be connected via appropriate conduits. The latter may enter the terminal housing at one or more of the hubs 36, 38, 39. Both housings include suitable provision for offset mounting of the panel board 20 in relation to a fixed support. Access to the terminal chamber 31 is afforded 'by means of an aperture in access panel 27 'closed by a threaded cover 40. The latter is fitted in explosion-proof sealed relation with the panel 27.

For the purpose of draining moisture which may accumulate within the housing 22, 30 and for releasing gaseous pressure due to an internal explosion while preventing the escape of hot gases or llame which might otherwise trigger an explosion in the surrounding atmosphere, each housing is provided with a drain and breather fitting 41. While such fittings may take a variety of forms, in the present instance they are of substantially identical construction and similar to the one disclosed in in United States Patent No. 2,405,927 issued August 13, 1956, on the application of Nils A. Tornblorn. For further details of such fittings, reference may be had to the disclosure of that patent. The uppermost one of the fittings 41, situated at the top of the terminal housing 30, may be provided with a suitable shroud 41A to prevent the entry lof foreign matter into the interior of the terminal chamber while permitting the venting of gaseous products in the manner just set forth. The safe dissipation of any pressures which may build up in either of the housings 24, 30 as a result of an internal explosion is thereby achieved.

Provision is made for detachably mounting a plurality of circuit breakers 21 with plug-in connections to the inner or reverse side of the actuating panel 25 via breaker access `port 28 in the housing Wall opposite the actuating panel (FIGS. l', Zand 3). For this purpose the actuating panel 25 has on its inner or reverse side a multiple breaker mounting receptacle 42 adapted in this case to hold six of the circuit breakers 21. The mounting receptacle 42 comprises a plurality of pairs of individual receptacles 44, 45, 46, 47, 48, 49, respectively, each pair in this case being adapted to hold two circuit breakers. Registration pins 50 on the receptacles slidably engage corresponding recesses in each breaker casing and serve to position the breaker accurately in place. The receptacles also include sets of closely spaced resilient contact elements l, 52 which slidably receive corresponding prong elements 54, 55 fixed to the breakers 21. Connections between the terminals 51, 52 and their associated wiring may be made by means of terminal screws 56 (FIG. 3).

To permit actuation and resetting of the breakers 21 from the outside face of the actuating panel 27 by levers 26, each of the latter has fixed thereto a threaded stem 58 (not shown in detail) which fits into a corresponding ly threaded bore through the actuating panel 25, there being a sufficient number of threads on the stem 58 to maintain the explosion-proof integrity of the breaker housing 22. yRigidly fixed to the inner end of each stem 58 is an actuator arm 59 extending radially therefrom. Adjacent its projecting end, the arm 59 has a pivot pin 60 lmounted thereon. The latter drivingly engages one of a plurality of slider bars 61 confined on the breaker mounting receptacle 42. Each slider bar 61 is formed with a rectangular opening 62 which receives the pin 60 ofthe actuator arm 59, and a second and somewhat larger rect-angular opening 64 which receives the operating toggle lever of the circuit breaker.

In accordance with one aspect of the invention, provision is made for offset mounting of the panel board 20 on a wall or other fixed support with the actuating panel 25 and the access panel 27 both exposed for ready access. This is accomplished in the present instance by cantilever suspension of the panel board 20 on brackets 65, 66 so that it is substantially perpendicular to the wall or support A68. Both of the brackets are of a general U-shape when viewed in a horizontal plane. They are connected to the panel board 20 as by means of cap screws 69 which engage blind holes in internal bosses 69A in the wall of the breaker and terminal housings 22, 30. The brackets may be secured to the wall or support 68 in any suitable manner, as by means of cap screws 70.

In accordance with another aspect of the invention, advantage is taken of the spacing afforded by the brackets 65, 66 between the panel board 20 and the wall or support 68 to facilitate connection of external conduit With the panel board. Accordingly, as shown in FIGS. 1 and 2, the terminal housing 30 may be equipped with one or more hubs 39 in its wall adjacent the support 68. Each such hub is adapted to receive an entrance elbow 71 which may be oriented in any suitable direction to accommodate the external connecting conduit. As indicated in FIG. l, the elbow 71 may be positioned with equal facility in an upwardly or downwardly extending direction.

Turning now to FIGS. 5, 6 and 7, there are shown certain modified forms of sealed connector fitting adapted to be interposed in the wall 32 separating the breaker and terminal housings 22, 30. The fitting 72 in FIG. 5 resembles the fitting 33 shown in FIGS. 1 and 4 in that it may readily be threaded into a suitable hub in the wall 32. In this instance, the fitting 72 is formed of insulating material with a built-in seal and internal conductors connecting screw terminals 74. The latter are readily adapted for connection to the breaker receptacles in the housing 22 and to the incoming wiring from the conduits in the terminal housing 30.

The sealed connector fitting 75 of FIGS. 6 and 7 differs from those just described in that it is formed as an integral hub in the internal partition wall 32 between the housings 22, 30. The conductors 35 are held in spaced insulated relation through the fitting 75 as by means of an internal seal 76 of appropriate sealing material.

In FIGS. 8 and 9, there is shown a further modification of sealed connector fitting means between the breaker housing 22 and terminal housing 3). In this instance, duplex sealed connector-s 78 are utilized. Each connector 78 comprises an integral hub 79 formed in the partition wall 32 adjacent the corners of the housings. Each such hub 79 carries a plurality of the conductors 35 maintained in insulated spaced relation as by means of a seal 80.

Referring next to FIGS. l0 and l1, there is shown a further modified form of explosion-proof panel board 20A somewhat similar to the panel board 20 described earlier herein and also embodying the invention. In this case, however, the panel board 20A has one or more integral raceways S1 formed therein on the side adjacent the support 63. The raceways 81 extend from the terminal housing down along the side of the breaker housing and terminate at the bottom of the latter where they are adapted to connect with suitable external conduits. The panel board 20A is mounted in a manner similar to that described in connection with the panel board 2t) except for the fact that the lower bracket 66A is somewhat shorter than the upper bracket 65 'because it a-buts against the raceways 31 rather than against the side of the breaker housing 22.

I claim as my invention:

'1. An explosion-proof panel board for accommodating a plurality of circuit breakers and comprising the combination of a terminal housing, a single compartment circuit breaker housing integral `with said terminal housing, a single breaker actuating panel on said `breaker housing, means detachably mounting a plurality of circuit breakers on the inner side of said actuating panel with plug-in connections between each said circuit breaker and said actuating panel with said breakers disposed in said compartment, a breaker access panel on said breaker housing opposite said breaker actuating panel and having a single access port therein providing access to all of said circuit breakers, bracket means rigidly mounting said housings in substantially perpendicular and spaced rellation with a fixed support with said actuating panel and said access panel Iboth exposed, and at least one entrance fitting mounted on said terminal housing between the same and the fixed support to receive an external conduit.

2. An explosion-proof panel board for accommodating a plurality of circuit breakers and comprising the combination of a terminal housing, a single compartment circuit breaker housing, a single breaker actuating panel on said breaker housing, means detachably mounting circuit breakers on the innerside of said actuating panel with plug-in connections between each of said circuit breakers and actuating panel with said breakers disposed in said compartment, a breaker access panel on said breaker housing opposite said breaker actuating panel and having a single access port therein providing access to all of said circuit breakers, bracket means rigidly mounting said panel board in substantially perpendicular and spaced relation with a `fixed support with said actuating panel and said access panel -both exposed, and at least one entrance elbow mounted on said panel board and disposed between the same and the fixed support, said elbow being adapted for orientation in a variety of directions to receive an external conduit.

3. An explosion-proof panel board for accommodating a plurality of circuit breakers, said panel board comprising, in combination, a terminal housing, a single compertinent Circuit breaker housing fixed to said terminal housing, a plurality of circuit breakers, a breaker actuating panel mounted on one side of said breaker housing, means detachably mounting a plurality of said circuit breakers on the inner side of said actuating panel with plug-in electrical connections between each of said circuit breakers and actuating panel with said circuit breakers disposed in said compartment, a breaker access panel on another side of said housing disposed in opposed relation with said breaker actuating panel and having a single breaker access port therein, a detachable cover fitted on said 'breaker access port in explosion-proof relation therewith, and means connected to still another side of said breaker housing mounting said panel board on a fixed support with said actuating panel and said access panel both exposed.

4. An explosion-proof panel board as defined in claim 1, in which said terminal housing and said circuit breaker housing are separated by an internal partition which denes an explosion-proof barrier therebetween.

5. An explosion-proof panel board as defined in claim 4, in which said partition is provided with a sealed connector fitting carrying electrical conductors between said housings, said partition and sealed connector fitting physically isolating said housings from each other.

References Cited by the Examiner UNITED STATES PATENTS 4/36 Hastings 317-120 11/43 Bush 317-119 

1. AN EXPLOSION-PROOF PANEL BOARD FOR ACCOMMODATING A PLURALITY OF CIRCUIT BREAKERS AND COMPRISING THE COMBINATION OF A TERMINAL HOUSING, A SINGLE COMPARTMENT CIRCUIT BREAKER HOUSING INTEGRAL WITH SAID TERMINAL HOUSING, A SINGLE BREAKER ACTUATING PANEL ON SAID BREAKER HOUSING, MEANS DETACHABLY MOUNTING A PLURALITY OF CIRCUIT BREAKERS ON THE INNER SIDE OF SAID ACTUATING PANEL WITH PLUG-IN CONNECTIONS BETWEEN EACH SAID CIRCUIT BREAKER AND SAID ACTUATING PANEL WITH SAID BREAKERS DISPOSED IN SAID COMPARTMENT, A BREAKER ACCESS PANEL ON SAID BREAKER HOUSING OPPOSITE SAID BREAKER ACTUATING PANEL AND HAVING A SINGLE ACCESS PORT THEREIN PROVIDING ACCESS TO ALL OF SAID CIRCUIT BREAKERS, BRACKET MEANS RIGIDLY MOUNTING SAID HOUSINGS, IN SUBSTANTIALLY PERPENDICULAR AND SPACED RELATION WITH A FIXED SUPPORT WITH SAID ACTUATING PANEL AND SAID ACCESS PANEL BOTH EXPOSED, AND AT LEAST ONE ENTRANCE FITTING MOUNTED ON SAID TERMINAL HOUSING BETWEEN THE SAME AND THE FIXED SUPPORT TO RECEIVE AN EXTERNAL CONDUIT. 